Since discovered in 2004, as a new carbon material, graphene has immediately excited great interest among scientists. Graphene having a unique two-dimensional nanostructure is high in electron transport rate, conductivity, and thermal conductivity. Besides, graphene is a material of the highest mechanical strength ever known, which is also advantageous in stable chemical properties and good light transmittance. Graphene provides a very attractive prospect in many fields such as the semiconductor industry, energy storage materials, functional composite materials, sensors and bio-pharmaceutical fields. Thus, fundamental and application studies on graphene have become a focus among international researches.
The preparation method for graphene is the key issue as to whether the material can achieve practical applications. As research continues, many fields, including energy storage materials and functional composite materials, have proposed stricter requirements on the quality and production scale of graphene. Methods for preparing graphene reported in the prior art include mechanical stripping (K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, A. A. Firsov, Science 2004, 306, 666), epitaxial growth (C. Berger, Z. M. Song, X. B. Li, X. S. Wu, N. Brown, C. Naud, D. Mayou, T. B. Li, J. Hass, A. N. Marchenkov, E. H. Conrad, P. N. First, W. A. de Heer, Science 2006, 312, 1191), chemical vapor deposition (K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, K. S. Kim, J.-H. Ahn, P. Kim, J.-Y. Choi, B. H. Hong, Nature 2009, 457, 706), and oxidation-reduction preparation in the solution-phase (S. J. Park, R. S. Ruoff, Nature Nanotechnology 2009, 4, 217)
Among the above methods, mechanical stripping and epitaxial growth are low in production efficiency, and thus have difficulties in meeting the large-scale needs. Chemical vapor deposition may produce a successive graphene film having a large size; however, the graphene film produced is merely applicable to micro-nano electronic devices or transparent conductive film, but can not meet the large-scale needs in the fields of energy storage materials and functional composite materials.
Compared with the above three methods, the oxidation-reduction preparation in the solution-phase has significantly improved scale of production, but the fierce redox condition in the oxidation-reduction preparation in the solution-phase disclosed in the prior art results in many defects in the graphene product, and significantly deteriorates the quality and performance such as conductivity of graphene. Moreover, the conventional oxidation-reduction preparation in the solution-phase is complicated in process and has considerable difficulties in handling of the reaction waste liquid. In summary, none of the methods in the prior art is suitable for large-scale preparation of high-quality graphene.